<script src="https://cdn.bootcss.com/jquery/1.11.3/jquery.min.js"></script>
<link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">

<style>
    .container-small {
        max-width: 500px;
    }

    .btn.btn-primary {
        border-color: #a20;
        background-color: #a20;
    }
</style>

<!--bootstrap容器-->
<div class="container container-small">
    <h1>登录</h1>
    <form>
        <!--提示样式alert-->
        <div class="alert alert-success">登录成功~正在跳转...</div>
        <!-- 表单组样式form-group-->
        <div class="form-group">
            <label>用户名</label>
            <!--表单控件form-control-->
            <input class="form-control" type="text">
        </div>
        <div class="form-group">
            <label>密码</label>
            <input class="form-control" type="password">
        </div>
        <div class="form-group">
            <!--按钮btn原始按钮btn-primary块级按钮btn-block-->
            <button class="btn btn-primary btn-block" type="submit">登录</button>
        </div>
    </form>
</div>